The present invention relates to a solid state image pick-up device comprising an array of static induction transistor image sensors, each having a drain region of one conductivity type, a source region of one conductivity type, a gate region of a second conductivity type and a channel region of one conductivity type.
The static induction transistor image sensor (hereinafter referred to as SIT image sensor) has signal amplifying and switching functions as well as a photo-electrically converting function. Such a SIT image sensor has been described in detail in, for example, "Static Induction Transistor Image Sensors", IEEE TRANSACTIONS ON ELECTRON DEVICES, Vol. ED-26, No. 12, Dec., 1979, pp. 1970 to 1977.
In general, in order to pick-up an image of an object moving at a high speed, it is necessary to carry out the imaging with a higher shutter speed corresponding to the moving speed of the object. To this end, it is preferable to make the shutter speed adjustable over a wide range from 1/1000 second to several seconds. In a television camera having a known image tube, in order to read-out an image signal by effecting an interlace scanning at a field frequency of 60 Hz in the NTSC standard system, a photoelectric converting film of the image tube has to be charged-up at a rate of 1/60 second, and therefore the shutter speed can not be shorter than 1/60 second. Heretofore, in order to achieve a shorter shutter time than 1/60 second, use has been made of a mechanical shutter such as a rotary shutter provided in the front of the image tube. In such a mechanical shutter, the shutter speed is variable by changing the rotation speed of a rotary disc. It is apparent that the mechanical shutter provides serious problems in making the image pick-up device small in size and light in weight. Moreover, in the mechanical shutter, it is impossible or at least difficult to adjust the shutter speed at will. The above problem is also applied to a still camera comprising an image tube.
As the solid state image pick-up device, there has been developed a television camera comprising a charge coupled device (CCD). In such a device, an electronic shutter function can be attained by changing the change carrier storing time in the photoelectric converting action. Then, the shutter speed can be easily adjusted at will by externally applying an electrical signal to the device. However, in the solid state image pick-up device comprising SITs, such an electronic shutter function can not be achieved.